V. On the physical action of the microphone
Hughes · The London Edinburgh and Dublin Philosophical Magazine and Journal of Science · 1878
The following notes of salts which have not yet been fully examined may be useful.Cyanide of Potassium, as a cryogen, gives a temperature of --21°'1.]~he cryohydrate forms at --33 °, with a carbonicacid and-ether cryogen.Compare § 170. Oxalate of Sodiumforms a cryohydrate at --1°"7 C. Employed as cryogens, the following temperatures were obtained from the corresponding salts :--O Chloride of cadmium -8"3 C. ,, nickel .... --10"35 Citrate of sodium .... --11"3 Acetate of calcium .... --11"8 Chloride of cobalt .... --15"35 , manganese .. --28"0 Those of these bodies which evolve heat on mixture with water would, when cooled, depress the temperature more.Thus the chloride of manganese scarcely showed signs of a cryohydrate at --40 ° C.Pormate of Sodium, as a cryogen, gives --14°'3.A concentrated solution becomes semisolid at --14 °, but does not become opaque or completely solid in a salt-ice cryogen